Dual-Task Interference: The Effects of Verbal Cognitive Tasks on Upright Postural Stability in Parkinson's Disease

Table 2

Means (and standard deviations) for each postural variable, separated by group.

Healthy older adults
	COPL (m)	BOSml (%)	BOSap (%)
No task	0.79 (0.11)	3.71 (1.32)	8.74 (2.55)
Numerical recitation	0.94 (0.15)	4.23 (1.52)	9.31 (3.11)
Monologue	1.26 (0.23)	7.35 (4.19)	14.0 (6.52)
Parkinson's disease
	COPL (m)	BOSml (%)	BOSap (%)
No task	0.65 (0.11)	4.11 (2.57)	8.16 (2.07)
Numerical recitation	0.76 (0.16)	5.21 (3.87)	9.54 (3.36)
Monologue	0.82 (0.16)	5.11 (3.03)	10.20 (3.85)

Where COPL = length of centre of pressure path; BOSml = medial-lateral centre of pressure excursion range; BOSap = anterior-posterior centre of pressure excursion range.